Tony Eaton has made an emotional appeal for anyone with information to come forward
The father of a hospital care worker shot dead on Merseyside six years ago said his family is in "purgatory".
Craig Eaton, a care worker at Alder Hey Children's Hospital, was shot at Molyneux Road, Kensington, on 24 February 2004.
His father Tony said his son's death was "senseless", and is appealing for anyone with information on his murder to come forward.
Police believe Mr Eaton was killed in a case of mistaken identity.
A £10,000 reward is being offered for information leading to the arrest and conviction of his killer.
Tony Eaton said: "For the last six years my family and I have been living in purgatory trying to come to terms with the senseless death of a son and brother who didn't have a bad bone in his body.
"Craig was a really hard working young lad who loved his job caring for children and did not have an enemy in the world.
"We have never come to terms with Craig's death and I would appeal to anyone who knows what happened on the night Craig was killed, and who is responsible, to come forward."
On the night of the murder, Mr Eaton boarded the number 26 Arriva bus on Belmont Road and travelled to Sheil Road, Kensington.
Police are still trying to trace some of the passengers who were on the bus.
Mr Eaton was making his way to a friend's house when he was shot twice.
Det Supt Lol Carr, of Merseyside Police, said: "We believe Craig may have been shot in a case of mistaken identity.
"He was a young man who was in the prime of his life and he had no link to any criminal elements."
Detectives are also trying to trace the movements of two cars which were in the Molyneux Road area on the night of Craig's murder.
A dark Green Ford Mondeo, registration number Y723 RJA, was seen driving past the scene of the shooting. It had been stolen from Kirkdale and was later recovered.
A silver/light Blue Volvo 740 GL saloon car was later seized by police. Officers want to speak to the car's previous owner.